Collisions between commercial ships and small vessels are unfortunately still a relatively common occurrence. From investigated accidents it follows that a proper and effective lookout and taking early avoiding action in accordance with the Colregs could have prevented the collisions in almost every instance.

Statistics from an Australian study revealed 63 reported collisions between commercial ships and small vessels between 1990 and 2017. The Nautical Institute also investigated three such incidents in its latest Mars Report. In all three, the organisation comes to more or less the same conclusions. Most important preventive actions are an effective lookout, not making assumptions about what the other vessel will do and taking early avoiding action.

Also read the following Mars Reports: General cargo vessel collides with fishing vessel after not acting on small CPA / Loaded tanker collides with a fishing vessel in a restricted waterway and low visibility / Distractions on the bridge contribute to collision between cargo and fishing vessel

Expectancy and confirmation bias

When looking at such accidents in general, The Nautical Institute also points to the importance of expectancy and confirmation bias.

The organisation quotes an insight published in one Australian report of such an occurrence (ATSB/333-MO-2017-007):

‘Human performance aspects that are relevant to some of these collisions include expectancy and confirmation bias. Expectations are based on past experience and other sources of information, and they strongly influence where a person will search for information, what they will search for and their ability to notice and recognise a target or relevant aspect of a situation (Wickens and McCarley 2008). If the expectations are incorrect, then a person will be less likely to detect the target or a relevant aspect of the target (such as the heading or speed).

People generally seek information that confirms or supports their hypotheses or beliefs, and either discount or do not seek information that contradicts those hypotheses or beliefs. When the available information is ambiguous, it will generally be interpreted as supporting the hypothesis. This confirmation bias is an inherent aspect of human decision-making and has been demonstrated to occur in a wide range of contexts (Wickens and Hollands 2000).’

If an assessment of another vessel’s heading and speed is based on limited or incomplete information, there is a significant likelihood it will be incorrect. However, aspects such as expectancy and confirmation bias mean an initial incorrect assessment may not be effectively identified and corrected.

The Nautical Institute gathers reports of maritime accidents and near-misses. It then publishes these so-called Mars Reports (anonymously) to prevent other accidents from happening.